Locking unit for a device for modifying the timing of charge change valves in internal combustion engines

ABSTRACT

A locking mechanism for a device ( 1 ) to modify the control timing of cylinder valves of an internal combustion engine, in particular for a vane-cell positioning device. The device ( 1 ) consists of a drive wheel ( 2 ) driven by a crankshaft of the internal combustion engine, said drive wheel having a cavity ( 6 ), and an impeller ( 8 ) permanently connected to the camshaft ( 7 ) that has at least one vane ( 12 ). In the cavity ( 6 ) of the drive wheel ( 2 ), at least one working chamber ( 15 ) is formed by intermediate walls ( 14 ) and each of these chambers is divided by an associated vane ( 12 ) into two hydraulic pressure spaces ( 16, 17 ). When pressure is applied by means of a hydraulic pressure medium, the pressure spaces ( 16, 17 ) effect a pivoting motion of the impeller ( 8 ) with respect to the drive wheel ( 2 ), whereas when the pressure is not applied to one of the pressure spaces ( 16, 17 ) the impeller ( 8 ) and the drive wheel ( 2 ) are mechanically coupled together. The mechanical coupling between the impeller ( 8 ) and the drive wheel ( 2 ) of the device ( 1 ) is accomplished by at least one axially moving vane ( 12 ) of the impeller ( 8 ) which is designed both as a vane pivoting element and as a locking element.

BACKGROUND OF THE INVENTION

The invention pertains to a locking mechanism for a device to modify thecontrol timing of cylinder valves of an internal combustion engine, andespecially to a vane-cell positioning device, including a drive wheeldesigned as an external rotor driven by a crankshaft of the internalcombustion engine through a traction means, said drive wheel having acavity formed by a perimeter wall and two side walls. The lockingmechanism also includes an impeller that is placed in this cavity anddesigned as an internal rotor, permanently connected to a camshaft ofthe internal combustion engine. This impeller has at least one vane onthe perimeter of its hub located in an axial notch and extendingradially out from the hub. In the cavity of the drive wheel, at leastone working chamber is formed by intermediate walls starting at theinside of the perimeter wall of the drive wheel and extending toward thelongitudinal centerline of the device. Each of these working chambers isitself divided into two hydraulic pressure spaces by a vane of theimpeller that extends into each working chamber. These hydraulicpressure spaces effect a pivoting motion and/or a fixing of the impellerwith respect to the drive wheel by selectively, simultaneously, or witha time delay applying pressure from a hydraulic pressure medium. Whenthe pressure is not applied in either of the pressure spaces, theimpeller and the drive wheel can be coupled with one anothermechanically in at least one preferred position with respect to oneanother.

A device of this type has already been categorized by patent U.S. Pat.No. 48,58,572. In a preferred embodiment of this device, six equallysized working chambers are formed between six intermediate walls locatedin the cavity of the drive wheel opposite one another in a circulardirection. These working chambers themselves are each divided into afirst and a second pressure space, which are liquid-tight with respectto one another, by means of six vanes fastened rigidly to the hub of animpeller connected to the camshaft. The mechanical coupling between theimpeller and the drive wheel of the device is accomplished througheither one of two spring-loaded locking pins located in a radial hole inan intermediate wall of the drive wheel engaging into a radial receivinghole located between two vanes of the hub in alternating fashion. Thisoccurs when the vanes of the impeller are at one of their two endpositions at the intermediate walls of the drive wheel and if theapplied pressure from the hydraulic pressure medium is turned off at thefirst or second pressure space of the device. If, then, the pressure isreapplied to the respective pressure space and a specific value of thepressure of the pressure medium is exceeded, the respective lockedlocking pin is pushed completely into the radial hole in theintermediate wall and out of the receiving hole in the hub so that themechanical coupling between the impeller and the drive wheel is againdisengaged.

Another possibility of mechanical coupling between the impeller and thedrive 20 wheel is suggested by the solution published in patent DE-OS196 23 818. This solution is specifically intended for a pivoting-vanepositioning device, which is comparable with respect to its basic designto a vane-cell positioning device, but with more massive vanes at theimpeller and differing from it at most by only one to four workingchamber(s). In this solution, an axial locking pin is located within oneof the radial vanes of the impeller. This locking pin can be shiftedparallel to the longitudinal centerline of the device and when thepressure of the hydraulic pressure medium decreases it is pushed by theforce of a spring into an axial engagement opening in a front plate thatis connected to the drive wheel. The engagement opening is hydraulicallyconnected to one of the pressure spaces inside the device so that thepressure medium can also act on the front surface of the locked lockingpin located in the engagement opening. When a certain value of pressureof the pressure medium is exceeded, the pressure medium pushes this pinagain into its unlocked position within the vane.

However, these mechanical couplings between the impeller and the drivewheel of a vane-cell or pivoting-vane positioning device, in one casedesigned as a radial locking pin and in the other case designed as anaxial locking pin, have the disadvantage in that they are constructedfrom a number of additional individual parts. Due to the necessaryincrease in expense to manufacture and install these parts, this raisesthe manufacturing costs of a vane-cell or pivoting-vane positioningdevice designed in this manner. Moreover, the danger exists in thedesign of the locking pin as simple pressure pins in both variations inthat they deform when large stresses are absorbed from either rotatingdirection of the impeller, such that re-locking the device correctly canno longer always be guaranteed in every case. Also, the front surface ofthese types of locking pins, designed as pressure pins, is designed tobe relatively small as a pressure application surface used for unlockingso that the pressure of the pressure medium sufficient to unlock onlybuilds relatively late in the process, thus delaying the unlocking timeof the device, which is detrimental.

SUMMARY OF THE INVENTION

The object of the invention is to produce a locking mechanism for adevice to modify the control timing of cylinder valves of an internalcombustion engine, in particular for a vane-cell positioning device.This locking mechanism distinguishes itself by having as small a numberof individual parts as possible, thus lowering the manufacturing andinstallation costs, as well as by having as large a pressure applicationsurface as possible for the hydraulic unlocking of the device forguaranteeing continued correct locking of the device, even afterabsorbing large stresses in both rotating directions of the impeller.

This object is met by means of the invention with a device according tothe preamble of claim 1 in that the mechanical coupling between theimpeller and the drive wheel of the device can be produced by at leastone vane of the impeller being designed as an impeller pivoting elementas well as at the same time being designed as a locking element. Whenthe pressure of the hydraulic pressure medium necessary to pivot theimpeller is not met, the vane can be fixed into a locked positionrelative to the drive wheel using an auxiliary energy source, and when acertain pressure of the hydraulic pressure medium is exceeded, it can befixed by the pressure of the pressure medium into an unlocked orpivoting position within the working chamber associated with it.

An effective further development of the invention in this regard is thateach vane of the impeller that is designed as a locking element islocated within its axial notch in the hub of the impeller and is free tomove axially, and one of its radial surfaces that seals against the sidewalls of the drive wheel is locked within an associated radial alignmentnotch on the inside of one of the side walls of the drive wheel in oneor more locked positions of the device. In this regard, it is preferredthat all vanes of the impeller, regardless of whether they are designedas locking elements at the same time or not, are also spring-mountedradially, preferably lying against a leaf or helical spring locatedinside their axial notch in the hub. In this way, a constant contactpressure is produced against the inside of the perimeter wall of thedrive wheel, thus improving the pressure medium seal between therespective bordering pressure spaces at the free end of each vaneopposite the spring.

It has proven to be cost effective to design only one vane of theimpeller as a locking element of the device, independent of the numberof vanes. This locking element, is fixed to the drive wheel in only oneof its end positions, corresponding to mounting the device at an inletor exhaust camshaft. The required radial alignment notch of this vane ispreferred to be incorporated into the sidewall of the drive wheel thatis furthest from the camshaft in the immediate vicinity of one of theintermediate walls of the drive wheel that border its working chamber orpressure spaces and that runs parallel to their stopping surfaces.However, it is also possible to locate the radial alignment notch in thesame fashion in the sidewall of the drive wheel nearest the camshaft.Likewise, those solutions should be included under the scope ofprotection of the invention that have two or more vanes designed aslocking elements that can all be locked in one of their end positionsor, by arranging another radial alignment notch in the sidewall of thedrive wheel furthest from or nearest to the camshaft inside each workingchamber, in either of their end positions. It is also possible to designone or more vanes of the impeller so that it can be fixed in the firstend position and to design one or more vanes to be fixed in the otherend position of the vane and/or, by arranging other radial alignmentnotches in the working chambers, to also fix the impeller in one or moreposition(s) between the end positions if certain operating conditions ofthe internal combustion engine require it.

In refining the locking mechanism according to the invention, it issuggested moreover that the radial alignment notch in the inside of thesidewall of the drive wheel that is furthest from the camshaft have alength similar to the height of the lockable vane and to have a recesson a part of its length resulting from another pressure medium guidenotch. The non-recessed parts of the notch base of the radial alignmentnotch are provided as axial stopping surfaces for the lockable vane.Moreover, the width of the radial alignment notch, which approximatesthe thickness of the lockable vane, is dimensioned such that the vanecan be easily slid into the alignment notch while preventing chatteringof the vane in its fixed position. Also, the side surfaces of thealignment notch act as stopping surfaces for the lockable vane in bothrotating directions of the impeller. To make sliding the vane into theradial alignment notch more easily, it is also advantageous to chamferor round off the longitudinal edges of the sealing surface of the vanethat works together with the alignment notch, or as an equivalentmeasure to design the alignment notch to be slightly conical or to roundoff its edges.

Another feature of the locking mechanism according to the invention isthat the pressure medium guide notch inside the radial alignment notchis connected to the pressure medium feed line feeding the pressure spaceof the device containing the radial alignment notch at its end nearestto the longitudinal centerline of the device. This connection is madeusing a pressure medium fill chute leading from the inside of thesidewall of the drive wheel that is furthest from the camshaft to thebase of the pressure medium guide notch. By means of this pressuremedium fill chute, the hydraulic pressure medium finds its way, startingfrom a pressure medium feed line that leads from the hub of the impellerto the pressure space of the device containing the radial alignmentnotch, into the pressure medium feed notch inside the radial guidenotch. In this way, the pressure of the hydraulic pressure medium actingon the part of the radial sealing surface of the vane that does not lieagainst the stopping surfaces of the alignment notch in the lockedposition of the vane, which makes it a surface where pressure can beapplied, causes the vane to shift axially into its unlocked positionwhen a certain pressure value is exceeded. Alternatively, the lockedvane can be hydraulically unlocked in the same way if instead of thepressure medium guide notch being contained within the radial alignmentnotch, a pressure application notch is incorporated into the sealingsurface of the vane that works together with the alignment notch,preferably parallel to the longitudinal edges of this sealing surface.The pressure medium fill chute has the same arrangement and design as inthe previously mentioned design of the alignment notch with the recessedpressure medium guide notch. It has proven to be advantageous in thisregard if the intermediate walls in the cavity of the drive wheel eachhave pressure medium pockets, designed as cutouts in a known fashion, attheir stopping surfaces that define the locking position of theimpeller. These pressure medium pockets accelerate the filling of thepressure spaces, which are at minimum volume when the device is in itslocked position, when pressure is applied to them. Thus, the pressuremedium feed line to the pressure space containing the radial alignmentnotch and which is at minimum volume in the locked position of thedevice first flows into the pressure medium pocket of the adjoiningintermediate wall. The pressure medium then flows into the pressuremedium fill chute of the pressure medium guide notch inside the axialalignment notch. In this way, when pressure is applied to the pressurespaces that are at minimum volume, it is possible to transfer thepressure from the pressure medium nearly unhindered to the part of theradial sealing surface of the locked vane, which is designed as apressure application surface, and a rapid and safe axial shift of thevane into its unlocked position is guaranteed.

With respect to manufacturing, it has been shown to be especiallyadvantageous to sinter the alignment notch, the pressure medium guidenotch and the pressure medium fill chute into the sidewall of the drivewheel that is furthest from the camshaft. This non-cutting manufacturingprocess prevents, at the outset, the functioning of the device frombeing affected by any milling residue later on. It is also possible,however, to incorporate the alignment notch, the pressure medium guidenotch and the pressure medium fill chute into the sidewall of the drivewheel by cutting manufacturing processes such as by milling or similarprocesses. However, careful cleaning work of the work space isessential.

Furthermore, an advantageous refinement of the invention is suggested inthat the necessary auxiliary energy to fix the vane into its lockedposition is produced using at least one pre-tensioned spring meansacting in the locking direction. To this end, for example, two helicalcompression springs or conical springs have proven to be especiallyadvantageous, each located inside an axial base hole in the radialsealing surface of the lockable vane nearest the camshaft. The number ofthese springs and their tension can be varied as desired depending onthe space requirements or can be adjusted according to the conditions.In order to prevent relative motion between the spring means arranged inthis way and the sidewall of the drive wheel nearest the camshaft, aswell as to guide the spring means, which can easily buckle in thesetypes of applications, each spring means is designed to fit over anaxial guide pin inside its base hole in the lockable vane, to furthersolidify the locking mechanism according to the invention. This guidepin has a cross sectional enlargement at its end nearest the camshaftthat can be countersunk into the base hole in the unlocked position ofthe vane. In this way, the spring media are supported on one hand at theback of the base hole and on the other hand at the annular crosssectional transition surface of their guide pins, whereas the endsurface of each guide pin nearest the camshaft permanently sits againstthe sidewall of the drive wheel nearest the camshaft. Therefore, toreduce the friction between the guide pins and the sidewall of the drivewheel nearest the camshaft during the positioning operation of thedevice, the end surface of each spring media guide pin nearest thecamshaft is preferably designed as convex, which is another feature ofthe invention, so that it slides against the inside of the sidewall ofthe drive wheel nearest the camshaft only at points. To further improvethe wear resistance of the guide pins, it is advantageous moreover todesign them to be case-hardened or, instead of the convex design of theend of the guide pin nearest the camshaft, to provide this end with aplastic layer to reduce the friction. Also, the guide pins can bedesigned completely as injection molded plastic parts or as cast partsmade of zinc or brass.

Finally, it is suggested as another feature of the locking mechanismaccording to the invention that the outside surface of each guide pin aswell as the outside surface if its cross sectional enlargement in thelongitudinal direction of the base hole be designed conically and thateach guide pin have a pressure equalization line for the hydraulicpressure medium, designed as a penetration hole along its longitudinalcenterline. By designing the conical guide pins to be narrower in thedirection away from the camshaft, sliding them into their base holeswhen the vane is unlocked is made easier. This can also be accomplishedby designing the base holes in the lockable vanes and theircountersinking for the cross sectional enlargement of the guide pins tobe conical instead of the outer surfaces of the guide pins. The pressureequalization line in the guide pins designed as a penetration holefacilitates the displacement of hydraulic pressure medium located in thebase holes when the vane is unlocked. This can also be done throughother suitable means such as, for example a flattening on one side ofthe outer surfaces of the guide pins or by means of a threaded drainagenotch in the outer surface of each guide pin.

The locking mechanism according to the invention for a device to modifythe control timing of cylinder valves of an internal combustion engineof the vane-cell positioning type thus has, in contrast to the lockingmechanisms known from the state of the art, the advantage that only aminimum of additional individual parts or work steps are necessary toaccomplish a locking together of the impeller with the drive wheel inone or more positions. This is because of the simultaneous use of a vaneof the impeller as a pivot- and a locking element. In this way, thelocking mechanism according to the invention differentiates itself fromthe known locks advantageously by an enormously favorable cost formaterial and manufacturing, such that the manufacturing costs for avane-cell positioning device having this type of lock increases onlyslightly compared to vane-cell positioning devices without locks.Moreover, the locking mechanism according to the invention isdifferentiated through a high functional safety with respect to theabsorption of large stresses in both rotating directions of the impellersince the entire radial length of the vane which functions as a lockingelement is fixed in an alignment notch incorporated into a sidewall ofthe drive wheel with the same length. Thus, the vanes force absorptioncapability is sufficient for sustained, correct locking. Likewise, theradial sealing surface of the vane used to unlock the vane is largerthan the end surface of known locking pins so that the pressure of thepressure medium necessary to unlock the vane is reduced, as is the timeto unlock the vane.

A characteristic feature of the locking mechanism according to theinvention is, moreover, that in the locked position of the lockablevane, a hydraulic short-circuit between the pressure spaces borderingthe vane occurs since by axially shifting it between the sealing surfaceof the vane closest to the camshaft and the inside of the sidewall ofthe drive wheel closest to the camshaft, a gap arises havingapproximately the same depth as the radial alignment notch. What resultsis that when pressure is applied to the minimum-volume pressure spacesin the locked position, both pressure spaces bordering the locked vaneare filled with the pressure medium at the same time first before thevane is unlocked. This effect, which in and of itself is undesirable,nonetheless has the advantage, in particular with regard to the lockingof the vane in an intermediate position lying between its end positions,in that the impeller is already being hydraulically held in its positionrelative to the drive wheel—directly after being unlocked—by at leastone pair of pressure spaces of the device, and that this pair ofpressure spaces is completely vented due to the bypassing of thehydraulic pressure medium.

To prevent the hydraulic short-circuiting between the pressure spacesbordering the lockable vane and the effects resulting therefrom, it isonly necessary to leave out the pressure medium pocket at the stoppingsurface of the intermediate wall in the cavity of the drive wheel thatthe lockable vane lies against in the locked position. This allows thehydraulic pressure medium to first only flow into the other pressurespaces, which as before are designed with pressure medium pockets, whenpressure is applied accordingly, whereas the pressure medium feed lineto the minimum-volume pressure space bordering the lockable vane isblocked by means of the respective intermediate wall of the drive wheel.However, since in this case the pressure medium feed line is, as before,connected to the pressure medium fill chute, thus making it possible tohave a pressure medium flow into the radial alignment notch of thelocked vane, this at least will be unlocked by the application ofpressure. Filling the minimum-volume pressure space at the borderinglockable vane is then possible subsequent to the unlocking of the vanewhen the impeller rotates relative to the drive wheel as a result offilling the other minimum-volume pressure spaces, thus automaticallydisengaging the block of the pressure medium feed line due to theintermediate wall of the drive wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in more detail below on the basis of apreferred embodiment. In the drawings, the following is shown:

FIG. 1 is a longitudinal section through a vane-cell positioning devicewith a locking mechanism according to the invention;

FIG. 2 is a top view of the vane-cell positioning device with a lockingmechanism according to the invention with the sidewall of the drivewheel that is furthest from the camshaft removed;

FIG. 3 is an enlarged view of the area indicated by an X in FIG. 1 of avane of the impeller designed as a locking element according to theinvention;

FIG. 4 is an enlarged view of the area indicated by a Y in FIG. 2 of avane of the impeller designed as a locking element according to theinvention;

FIG. 5 is a top view of the inside of the sidewall of the drive wheelthat is furthest from the camshaft with a radial alignment notchaccording to the invention;

FIG. 6 is an enlarged view of the area indicated by a Z in FIG. 5 of theradial alignment notch in the sidewall of the drive wheel that isfurthest from the camshaft;

FIG. 7 is an enlarged view of section A—A according to FIG. 5 along thelongitudinal centerline of the radial alignment notch in the sidewall ofthe drive wheel that is furthest from the camshaft; and

FIG. 8 is an enlarged side view of a guide pin for the spring media toproduce the auxiliary energy for the lockable vane of the impelleraccording to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 and 2 clearly depict a device 1 designed as a vane-cellpositioning device to modify the control timing of cylinder valves of aninternal combustion engine. This device includes a drive wheel 2designed as an external rotor which is driven through connection with acrankshaft, not shown, of the internal combustion engine by means of atraction means, as well as an impeller 8 designed as an internal rotorwhich is permanently connected to a camshaft 7 of the internalcombustion engine. FIGS. 1 and 2 also show that the drive wheel 2 has acavity 6 formed by a perimeter wall 3 and two sidewalls 4, 5, in whichfour working chambers 15 are formed by four intermediate walls 14extending from the inside 13 of the perimeter wall 3 toward thelongitudinal centerline of the device 1. The impeller 8, having fourvanes 12 at the perimeter 9 of its hub 10, each of which is located inan axial notch 11 and extends out away from the hub 10 radially, isplaced in this cavity 6. These vanes 12 each extend into a workingchamber 15 in the drive wheel 2 and divide it into two hydraulicpressure spaces 16, 17. By selectively, simultaneously, or with a timedelay applying pressure to these pressure spaces 16, 17 using ahydraulic pressure medium, the impeller 8 can be pivoted and/or fixedwith respect to the drive wheel 2. This rotates the camshaft 7 relativeto the crankshaft of the internal combustion engine in a known fashionand/or is hydraulically held.

In order to prevent undesired noise, due to the alternating moments ofthe camshaft 7, which occurs when the vane 12 of the impeller 8 hits theintermediate walls 14 of the drive wheel 2 at a high frequency when theinternal combustion engine is started (at which point the device 1 islocated in its most pressure-less state), at least one vane 12 of theimpeller 8 of the device 1 is designed both as an impeller pivotingelement and at the same time as a locking element. This is for thepurposes of creating a mechanical coupling between the impeller 8 andthe drive wheel 2. This vane can be fixed in a locked position at thedrive wheel 2 using an auxiliary energy means when the pressure of thehydraulic pressure medium needed to pivot the impeller 8 is not met. Itcan also be fixed in an unlocked or pivoting position inside the workingchamber 15 associated with it when the pressure of the pressure mediumexceeds a certain hydraulic pressure.

In FIGS. 2 and 3, it is seen that of the four vanes 12 of the impeller8, which are all spring-mounted radially inside their axial notch 11 inthe hub 10, lying on leaf springs 23 to produce a continuous contactpressure of their free ends 24 against the inside 13 of the perimeterwall 3, only one vane 12 is designed as a locking element. It shiftsaxially inside of its axial notch 11 in the hub 10 of the impeller 8,and its radial surface 18 which seals against the sidewall 4 of thedrive wheel 2 locks together with a radial alignment notch 20 on theinside 21 of the sidewall 4, as shown in FIGS. 5 through 7. In theembodiment shown, this axial alignment notch 20 is in the directvicinity of the intermediate wall 14 of the drive wheel 2, which bordersthe working chamber 15 of the lockable vane 12 and its pressure space16. It is also sintered into the sidewall 4 of the drive wheel 2 that isfurthest from the camshaft, running parallel to its stopping surface 25,which is described in more detail in FIG. 4. This enables the vane 12 tobe fixed only at one of its end positions, or in concrete terms at thestart position of the camshaft 7 in relation to the drive wheel 2 thatis best for the starting of the internal combustion engine.

Moreover, FIG. 3 shows that the radial alignment notch 20 on the inside21 of the sidewall 4 of the drive wheel 2 that is furthest from thecamshaft has a length that is very close to the height of the lockablevane 12 and part of its length is slight recessed by means of anotherlikewise sintered pressure medium guide notch 26. As shown in FIGS. 6and 7, the parts of the notch base of the radial alignment notch 20 thatare not recessed are provided as axial stopping surfaces 27 for thelockable vane 12 in its fixed position. They also show that the pressuremedium guide notch 26 within the radial alignment notch 20 has apressure medium fill chute 28 at its end closest to the longitudinalcenterline of the device 1 which leads from the inside 21 of thesidewall 4 of the drive wheel that is furthest from the camshaft to thebase of the pressure medium guide notch 26. This fill chute also isincorporated by sintering. Thus, as shown in FIG. 4, this pressuremedium fill chute 28 connects the pressure medium guide notch 26 to thepressure medium feed line 29 that feeds the pressure space 16 of thedevice 1 containing the radial alignment notch 20. A pressure mediumpocket 30 incorporated into the stopping surface 25 of the intermediatewall 14 of the drive wheel 2 also accomplishes this. The result is thatthe locked position of the device 1 is disengaged and the lockable vane12 is returned to its moving, unlocked position as the pressure space 16is subjected to pressure.

Furthermore, FIG. 3 shows that the necessary auxiliary energy to fix thevane 12 in its locked position can be produced using two spring means 31that are each located inside an axial base hole 32 in the sealingsurface 19 of the lockable vane 12 closest to the camshaft and that aredesigned as conical springs. These spring means act in the lockingdirection with a certain pre-loaded tension. Each of these spring means31 fit over an axial guide pin 33, enlarged in FIG. 8, inside their baseholes 32 in the lockable vane 12. This guide pin has an enlargement incross section 34 at its end closest to the camshaft that can becountersunk into the base hole 32. In this way, the spring means 31 aresupport on one hand at the back 35 of the base hole 32 and on the otherhand at the annular surface 36 at the transition of cross section of theguide pin 33 and are secured against buckling during the relative motionbetween the drive wheel 2 and the impeller 8.

Finally, it can also be seen in FIG. 8 that the end surface 37 of eachguide pin 34 closest to the camshaft is designed as convex to reduce thefriction between the guide pins 33 and the sidewall 5 of the drive wheelclosest to the camshaft, thus gliding against the inside 22 of thesidewall 5 only at points. Moreover, the outer surface 38 of each guidepin 33 as well as the outer surface 39 of its enlarged cross section 34is designed as conical, as shown in the same illustration, in order tomake the sliding of the guide pins 33 into their base holes 32 easierwhen the vane 12 is unlocked. A pressure equalization line 40, designedas a passage along the longitudinal centerline of the guide pins 33,serves to facilitate the displacement of the hydraulic pressure mediumlocated in the base holes 32.

ELEMENT LIST

1 Device

3 Perimeter Wall

2 Drive wheel

4 Sidewall furthest from the camshaft

5 Sidewall nearest to the camshaft

6 Cavity

7 Camshaft

8 Impeller

9 Perimeter of the impeller

10 Hub

11 Axial notch

12 Vane

13 Inside of the perimeter wall

14 Intermediate walls

15 Working chamber

16 Pressure space

17 Pressure space

18 Sealing surface furthest from the camshaft

19 Sealing surface nearest to the camshaft

20 Alignment notch

21 Inside

22 Inside

23 Leaf spring

24 Free end

25 stopping surfaces

26 Pressure medium guide notch

27 Stopping surfaces

28 Pressure medium fill chute

29 Pressure medium feed line

30 Pressure medium pockets

31 Spring media

32 Base hole

33 Guide pin

34 Cross section enlargement

35 Back

36 Cross sectional transition surface

37 End surface

38 Outside surface

39 Outside surface

40 Pressure equalization line

What is claimed is:
 1. A device to modify the control timing of cylindervalves of an internal combustion engine, comprising a drive wheel (2)designed as an external rotor driven by a crankshaft of the internalcombustion engine through a traction means, said drive wheel having acavity (6) formed by a perimeter wall (3) and two side walls (4, 5),said device also including an impeller (8) that is located in the cavity(6) and designed as an internal rotor, connected to a camshaft (7) ofthe internal combustion engine, said impeller having at least one vane(12) on a perimeter (9) of a hub (10) located in an axial notch (11) andextending radially out from the hub (10), wherein at least one workingchamber (15) is formed in the cavity (6) of the drive wheel (2) by meansof intermediate walls (14) starting at an inside (13) of the perimeterwall (3) of the drive wheel (2) and directed toward a longitudinalcenterline of the device (1), each of said working chambers beingdivided into two hydraulic pressure spaces (16, 17) by the associatedvane (12) of the impeller (8) that extends into the working chamber(15), said hydraulic pressure spaces effecting a relative rotation or ahydraulic clamping of the impeller (8) with respect to the drive wheel(2) by selectively, simultaneously, or with a time delay applyingpressure from a hydraulic pressure medium, whereas when the pressure ofthe pressure medium in the pressure spaces (16, 17) is less than neededto pivot or hold the impeller, the impeller (8) and the drive wheel (2)are coupled with one another mechanically in at least one preferredposition with respect to one another, characterized in that the couplingbetween the impeller (8) and the drive wheel (2) of the device (1) isproduced by at least one vane (12) of the impeller (8) designed as alocking element and being movable axially in the associated axial notch(11) on the hub (10), one of the radial sealing surfaces (18, 19) ofsaid vane sealing against the sidewalls (4, 5) of the drive wheel (2)capable of being fixed by means of an auxiliary energy source into alocked position within a radial alignment notch (20) on the inside (21or 22) of one of the side walls (4 or 5) of the drive wheel (2), andsaid vane being movable into an unlocked or pivoting position inside itsassociated working chamber (15) when a specific pressure of thehydraulic pressure medium is exceeded.
 2. A device according to claim 1,characterized in that only one vane (12) of the impeller (8) is providedat one time as a locking element of the device (1), and is fixed to thedrive wheel (2) in only one of the end positions with the radialalignment notch (20) being incorporated into the side wall (4) of thedrive wheel (2) furthest from the camshaft in the vicinity of one of theintermediate walls (14) of the drive wheel (2) bordering the workingchamber (15) and the pressure spaces (16, 17) and extend parallel tostopping surfaces (25).
 3. A device according to claim 1, characterizedin that the radial alignment notch (20) in the inside (21) of the sidewall (4) of the drive wheel (2) furthest from the camshaft has a lengththat is nearly equal to the height of the lockable vane (12) and has aslight recess on a part of its length due to another pressure mediumguide notch (26), wherein the parts of the notch base of the radialalignment notch (20) that are not recessed are provided as axialstopping surfaces (27) of the lockable vane (12) in its fixed position.4. A device according to claim 3, characterized in that the pressuremedium guide notch (26) inside the radial alignment notch (20) isconnected by a pressure medium feed line (29) to the pressure space (16)of the device (1) containing the radial alignment notch (20), saidconnection being at the end of the alignment notch that is closest tothe longitudinal axis of the device (1) and formed by a pressure mediumfill chute (28) that leads from the inside (21) of the side wall (4) ofthe drive wheel (2) furthest from the camshaft to a base of the pressuremedium guide notch (26).
 5. A device according to claim 3, characterizedin that the alignment notch (20), the pressure medium guide notch (26)and the pressure medium fill chute (28) are sintered into the side wall(4) of the drive wheel (2) furthest from the camshaft or into the sidewall (5) nearest to the camshaft.
 6. A device according to claim 1,characterized in that the auxiliary energy needed to fix the vane (12)in its locked position is produced by two helical compression or conicalpre-tensioned spring means (31) acting in the direction of locking, eachlocated inside an axial base hole (32) in the sealing surface (19) ofthe lockable vane (12) closest to the camshaft.
 7. A device according toclaim 6, characterized in that each spring means (31) is designed to fitover an axial guide pin (33) inside the base hole (32) in the lockablevane (12), said guide pin having an enlarged cross section (34) at anend closest to the camshaft that is countersunk into the base hole (32),wherein each of the spring means (31) is supported on one end at theback (35) of the base hole (32) and on the other end at an annular crosssectional transition surface (36) of the guide pin (33).
 8. A deviceaccording to claim 7, characterized in that the end surface (37) of eachof the guide pins (33) for the spring means (31) closest to the camshaftis convex and slides on the inside (22) of the side wall (5) of thedrive wheel (2) closest to the camshaft at contact points.
 9. A deviceaccording to claim 7, characterized in that the outer surface (38) ofeach of the guide pins (33) as well as the outer surface (39) of theenlarged cross section (34) are conically shaped in a longitudinaldirection of the base hole (32) and each guide pin (33) has a pressureequalization line (40) for the hydraulic pressure medium designed as apenetration along its longitudinal centerline.
 10. A device according toclaim 4, characterized in that the alignment notch (20), the pressuremedium guide notch (26) and the pressure medium fill chute (28) aresintered into the side wall (4) of the drive wheel (2) furthest from thecamshaft or into the side wall (5) nearest to the camshaft.